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Lorriman
Tinkerer
Username: Lorriman
Post Number: 4
Registered: 06-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, May 14, 2009 - 07:01 am: | 
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I would love to hear from people with AL-1 experience but more general advice very welcome as I don't expect there is so much AL-1 experience out there.
My Canon AL-1 viewfinder focusses 3cm behind the real point of focus (ie. I get frontfocus). The electronic focus indicator is accurate but I prefer focusing with the viewfinder. I've tested this with scotch tape at the film plane and macro on my digi cam which gives me the equivalent of a 10x loupe. The focus error is consistent between two lenses, an FL55/1.2 and FD135/2.5. I'll be taking relatively close portraits so this error is a pain.
I am assuming that the focus screen needs adjusting. Is this usually an easy job for any SLR? Would it usually require partial dismantlement, or just turning some easily accessed screws?
I have no tools and no experience but I like to fiddle and the camera only cost £18. What do you think is my likely expenditure in tools, excluding a loupe, if I were to try this? |
Tom_cheshire
Tinkerer
Username: Tom_cheshire
Post Number: 9
Registered: 04-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, May 14, 2009 - 07:52 am: |
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Well, if you can't get it going, I will swap you something for the 55mm lens which I could use. |
Lorriman
Tinkerer
Username: Lorriman
Post Number: 5
Registered: 06-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, May 14, 2009 - 08:05 am: |
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an FD 55/1.2, perhaps?  |
Glenn
Tinkerer
Username: Glenn
Post Number: 576
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, May 14, 2009 - 02:35 pm: |
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Adjusting the screen is a major job, but with the prism removed you could use your digi cam as a substitute for the proper optical jig.
You will need a set of small crosshead screwdrivers to remove the top-plate and prism.
You will have to construct a simple jig to hold the camera at a fixed distance - about 1ft greater than min focus of 55mm lens - from a focus test chart. Fasten stripped camera on jig and focus chart on the scotch tape, reposition digi cam over screen and adjust screen until image is in focus. You should then remove the test chart and focus on an object at infinity. The screen and scotch tape images may/may not be, both in focus. If both images are sharp just re-assemble: however if you still have an error you will have to keep altering the screen until you reach the best compromise between the two images.
Personally I would leave well alone and use the electronics, the adjustment is much more than a fiddle - even to an experienced person. If you must use a screen, look out for one of the other types of basic A series bodies. |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 879
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, May 14, 2009 - 04:56 pm: |
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Have you checked the mirror rests? If I'm reading you right, I think the optical path from lens to screen is shorter than the path from lens to film ... this could happen if there was a film chip or a bit of dirt stuck to the tab where the mirror rests in the down position. Assuming no one has been poking around inside your camera, this seems like a more likely cause of the problem than the screen mysteriously readjusting itself over time. |
Lorriman
Tinkerer
Username: Lorriman
Post Number: 6
Registered: 06-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, May 14, 2009 - 05:15 pm: |
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Oh dear, I feared that answer. Thanks for the advice, Glenn.
Strangely my Minolta XG-M is also in need of adjusting by 4cm (backfocus).
Can this problem be so common? I suppose people just get a CLA. |
Gez
Tinkerer
Username: Gez
Post Number: 84
Registered: 09-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, May 14, 2009 - 05:34 pm: |
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Christian Rollinger's Canon FD site is back on line and he has a free Canon AL-1 service manual. |
Lorriman
Tinkerer
Username: Lorriman
Post Number: 7
Registered: 06-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, May 14, 2009 - 06:20 pm: |
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Thanks for that, Rick.
I can't see anything untoward when I lift the mirror up.
Could a screen get adjusted by a camera drop? My XG-M recieved a bad knock. The AL-1 has brassing so perhaps it got knocked in it's lifetime. |
Glenn
Tinkerer
Username: Glenn
Post Number: 577
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, May 15, 2009 - 12:03 pm: |
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The screen could move out of adjustment due to a bad knock; however, the mirror assembly is the item more likely to be damaged - evidence from the badly knocked/dropped cameras I have looked at. Depending on how the mirror base locates on the stop and how the base is constructed, it is just possible for the metal base or stop to be bent.
As I do not know the construction of your XG-M I cannot comment on this model, but the AL-1 is quite robust in that department - Rick's mention of dirt or debris on the stop must be looked at before you do anything else.
Get the service manual from Christian's site, this will give you a good idea of what you can expect if you have to strip the AL-1 down.
http://www.canonfd.com/choose.htm |
Gez
Tinkerer
Username: Gez
Post Number: 85
Registered: 09-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, May 15, 2009 - 01:02 pm: |
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Lorriman, you are using very heavy lenses (particularly the 55mm 1.2) on a lightweight body, it may be worth checking if the mounting flange has worked loose. |
Mikel
Tinkerer
Username: Mikel
Post Number: 142
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, May 16, 2009 - 12:22 pm: |
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The XG-M has a "user" removable focus screen. I've seen them reinstalled upside down. It's just clipped into place, and a jolt could dislodge it.
The prism is held in place by a pair of strong springs. They don't fail in a jolt but the plastic they are keyed into can snap and then it is beyond practical repair. |
Lorriman
Tinkerer
Username: Lorriman
Post Number: 8
Registered: 06-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 27, 2009 - 04:19 am: |
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great. thanks for all the info folks. |
